CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
OPERATING ACTIVITIES:
Net income	$ 29,830	$ 39,111	$ 33,746
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	9,598	9,127	7,745
(Gain) loss on disposal of property, plant and equipment	17	(21)	156
Provision for doubtful accounts	195	15	214
Issuance of non-employee director shares	194	150	150
Deferred tax provision	752	1,708	568
Changes in operating assets and liabilities:
Accounts receivable	27,375	(19,605)	(19,353)
Inventories	5,466	5,453	(23,865)
Prepaid expenses	1,652	(1,529)	989
Other assets	321	609	60
Accounts payable	(10,881)	(2,165)	19,425
Accrued liabilities	(3,810)	2,279	2,062
Net cash flows from operating activities	60,709	35,132	21,897
INVESTING ACTIVITIES:
Purchases of property, plant and equipment	(17,500)	(17,391)	(13,342)
Proceeds from sale of property, plant and equipment	276	328	141
Net cash flows from investing activities	(17,224)	(17,063)	(13,201)
FINANCING ACTIVITIES:
Net proceeds (payments) under credit facility	(4,998)	(10,002)	5,000
Payments of cash dividends	(8,212)	(8,208)	(8,200)
Net proceeds (payments) on other long-term obligations	(400)	(367)	56
Finance lease obligation payments	(21)	(20)
Proceeds from exercise of stock options			179
Net cash flows from financing activities	(13,631)	(18,597)	(2,965)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND TEMPORARY INVESTMENTS	1,595	(437)	(589)
NET CHANGE IN CASH AND TEMPORARY INVESTMENTS	31,449	(965)	5,142
CASH AND TEMPORARY INVESTMENTS, beginning of period	26,072	27,037	21,895
CASH AND TEMPORARY INVESTMENTS, end of period	57,521	26,072	27,037
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash payments for interest	2,052	3,249	2,437
Cash payments for income taxes, net of refunds	$ 6,721	$ 10,067	$ 7,457